Interspinous spacer assembly

ABSTRACT

An interspinous spacer assembly ( 100 ) for insertion and/or implantation between spinous processes of adjacent superior and inferior vertebrae includes an interspinous spacer member ( 110 ) sized and configured for insertion into the interspinous space located between adjacent spinous processes and an engagement mechanism ( 105 ) for operatively coupling the spacer member to the adjacent spinous processes and for preventing migration of the assembly once implanted. The interspinous spacer assembly is adjustable to conform to the individual anatomy of a patient&#39;s spine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/US2009/053727, filed Aug. 13, 2009, which claims the benefit ofpriority to U.S. Provisional Patent Application No. 61/088,574, filedAug. 13, 2008, the disclosures of which are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates generally to orthopedics. Morespecifically, the present invention relates to an interspinous spacerassembly and associated methods for stabilizing the human spine.

BACKGROUND OF THE INVENTION

A human vertebra has a rearwardly projecting portion known as a spinousprocess. Bending or the natural aging and degeneration of the spine cancause the spinous processes of adjacent vertebrae to be moved towardeach other. This constricts the space in the spinal canal and foraminaand, thus, may cause pain. Such constriction, known as stenosis, can betreated by the use of an implant in the space between adjacent spinousprocesses.

Generally speaking there are two types of spinal stenosis: (1) hard orrigid spinal stenosis, or (2) soft or dynamic spinal stenosis. In bothcases, spinal stenosis may be caused by excessive growth of tissue dueto degeneration, loss of disc height, as well as disorders such asspondilolisthesis where the normal relative position and/or orientationof the adjacent vertebrae have been modified.

The most significant difference between the two types of spinal stenosisis generally that dynamic spinal stenosis may be treated withdistraction of the vertebra at the affected level while hard stenosisgenerally requires removal of the tissue that obstructs the spinal canalor foramina at the affected level. In case of tissue removal, thepatient generally must accept some loss of stability of the spine.Therefore, it is preferable to increase the stability of the spinalsegment by inserting an interspinous spacer between adjacent vertebraeto increase the stiffness of the segment and/or to restrict motion ofthat segment. Additional stability may be desirable and may beaccomplished by adding plates to rigidly fix the spacer to the spinousprocesses and eliminate motion at that segment (i.e. fusion).

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to an interspinous spacer assembly forimplantation and/or affixation between spinous processes of adjacentsuperior and inferior vertebrae. The interspinous spacer assemblypreferably includes a spacer member sized and configured for insertioninto the space between adjacent spinous processes and an engagementmechanism for operatively coupling the spacer member to the adjacentspinous processes and for preventing migration of the assembly onceimplanted. The interspinous spacer assembly is preferably adjustable sothat the user can conform the interspinous spacer assembly to theindividual anatomy of a patient's spine.

One preferred embodiment of the present invention is an interspinousspacer assembly for insertion into an interspinous space between aspinous process of a superior vertebral body and a spinous process of aninferior vertebral body. The interspinous spacer assembly may include atleast one interspinous spacer member sized and configured for insertioninto the interspinous space. Each spacer member may include a cranialpaddle for contacting an inferior surface of the spinous process of thesuperior vertebral body and a caudal paddle for contacting a superiorsurface of the spinous process of the inferior vertebral body. Thecranial paddle may be moveable with respect to the caudal paddle so thatan overall height of the spacer member is adjustable. The cranial andcaudal paddles each may include one of first and second lateralprojections extending therefrom or first and second lateral bores formedtherein. The interspinous spacer assembly may also include an engagementmechanism for operatively coupling the spacer member to the spinousprocesses of the superior and inferior vertebral bodies. The engagementmechanism may include a first member, a second member, a third memberand a fourth member. Each of the first, second, third and fourth membersmay include one of a bore for receiving one of the projections extendingfrom the cranial and caudal paddles or a projection for engaging one ofthe bores formed in the cranial and caudal paddles. The interactingprojections and bores may enable the cranial and caudal paddles torotate about an axis.

In alternate preferred embodiment of the present invention, the spacermember and engagement mechanism may both be formed from first, second,third and fourth interlocking plate portions such that (i) the firstplate portion interlocks with the second plate portion to form aninferior portion of the spacer member for contacting the superiorsurface of the spinous process of the inferior vertebral body; (ii) thethird plate portion interlocks with the fourth plate portion to form thesuperior portion of the spacer member for contacting the inferiorsurface of the spinous process of the superior vertebral body; (iii) thefirst plate portion interlocks with the third plate portion to form afirst lateral plate for contacting one side of the spinous processes ofthe superior and inferior vertebral bodies; and (iv) the second plateportion interlocks with the fourth plate portion to form a secondlateral plate for contacting a second side of the spinous processes ofthe superior and inferior vertebral bodies. The first, second, third andfourth plate portions may be moveably associated with respect to oneanother so that an overall width and an overall height of the spacerassembly are adjustable.

In another alternate preferred embodiment of the present invention, thespacer member may include a cranial paddle for contacting an inferiorsurface of the spinous process of the superior vertebral body, and acaudal paddle for contacting a superior surface of the spinous processof the inferior vertebral body. The spacer member may also include aspreading element for moving the cranial paddle with respect to thecaudal paddle to adjust an overall height of the spacer member. Theengagement mechanism may include first and second members operativelycoupled to one another.

In another alternate preferred embodiment of the present invention, thespacer member may include a cranial spacer portion for contacting aninferior surface of the superior spinous process and a caudal spacerportion for contacting a superior surface of the inferior spinousprocess. The cranial spacer portion may be moveably coupled to thecaudal spacer portion by a ratchet mechanism so that an overall heightof the spacer member is adjustable. The ratchet mechanism may include aplurality of teeth formed on an anterior end and a posterior end of thecaudal spacer portion for engaging at least one tooth formed on ananterior end and a posterior end of the cranial spacer portion.

In another alternate preferred embodiment of the present invention, thespacer member may include a cranial surface for contacting an inferiorsurface of the spinous process of the superior vertebral body, and acaudal surface for contacting a superior surface of the spinous processof the inferior vertebral body. The space member may also include a boreextending therethrough, wherein at least a portion of the engagementmechanism passes through the bore formed in the spacer member. Theengagement mechanism may also include a plurality of rotatable wingsextending from the spacer member for laterally engaging the spinousprocesses. The plurality of rotatable wings may be rotatable from afirst folded configuration to a second deployed configuration.

In another alternate preferred embodiment of the present invention, thespacer member and engagement mechanism may be formed from first andsecond interlocking members such that the first member interlocks withthe second member. The first and second members may be moveablyassociated with respect to one another and the spacer may have anadjustable width and height.

In another alternate preferred embodiment of the present invention, thespacer member and engagement mechanism may be formed from a firstmember, a second member and an intermediate spacer part. The firstmember may include a cranial spacer part for contacting an inferiorsurface of the spinous process of the superior vertebral body and afirst wing for contacting a first lateral side of the superior vertebralbody. The second member may include a caudal spacer part for contactinga superior surface of the spinous process of the inferior vertebral bodyand a second wing for contacting a first lateral side of the inferiorvertebral body. The intermediate spacer part may be slidably disposedbetween the cranial spacer part and the caudal spacer part of the firstand second members. The intermediate spacer part may also be operativelyassociated with a third wing and a fourth wing of the first and secondmembers for contacting a second lateral side of the superior andinferior vertebral body, respectively.

In another alternate preferred embodiment of the present invention, thespacer member may include a cranial surface for contacting an inferiorsurface of the spinous process of the superior vertebral body, a caudalsurface for contacting a superior surface of the spinous process of theinferior vertebral body. The spacer member may also include a ventralend and a dorsal end. The interspinous spacer member may include one ofa bore and a clip and the engagement mechanism may include the other oneof the bore and the clip. The bore may be operatively associated withthe clip so that the interspinous spacer member is rotatable withrespect to the engagement mechanism.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofpreferred embodiments of the application, will be better understood whenread in conjunction with the appended drawings. For the purposes ofillustrating the preferred interspinous spacer assemblies of the presentapplication, drawings of the preferred embodiments are shown. It shouldbe understood, however, that the application is not limited to theprecise arrangements, structures, features, embodiments, aspects, andinstrumentalities shown, and the arrangements, structures, features,embodiments, aspects, and instrumentalities shown may be used singularlyor in combination with other arrangements, structures, features,embodiments, aspects and instrumentalities. In the drawings:

FIG. 1 illustrates a posterior elevational view of a first preferredembodiment of an interspinous spacer assembly according to the presentinvention mounted to superior and inferior vertebrae;

FIG. 2 illustrates a side elevational view of the interspinous spacerassembly shown in FIG. 1;

FIG. 3A illustrates a side perspective view of an exemplary embodimentof a single headed bone screw that may be used in combination with theinterspinous spacer assembly shown in FIG. 1;

FIG. 3B illustrates a side perspective view of an exemplary embodimentof a double headed bone screw that may be used in combination withinterspinous spacer assembly shown in FIG. 1;

FIG. 4A is a partially exploded side perspective view of theinterspinous spacer assembly show in FIG. 1;

FIG. 4B is a cross-sectional view of the interspinous spacer assemblytaken along line 4B-4B from FIG. 4A;

FIG. 5 illustrates a side perspective view of a second preferredembodiment of an interspinous spacer assembly in accordance with thepresent invention;

FIG. 6A is a posterior elevational view of the interspinous spacerassembly shown in FIG. 5, the interspinous spacer assembly being in afirst, collapsed configuration;

FIG. 6B is a posterior elevational view of the interspinous spacerassembly shown in FIG. 5, the interspinous spacer assembly being in asecond, expanded configuration;

FIG. 7 illustrates a side perspective view of a third preferredembodiment of an interspinous spacer assembly in accordance with thepresent invention;

FIG. 8 illustrates a side perspective view of a fourth preferredembodiment of an interspinous spacer assembly in accordance with thepresent invention;

FIG. 9 illustrates a side perspective view of a fifth preferredembodiment of an interspinous spacer assembly in accordance with thepresent invention;

FIG. 10 illustrates a side perspective view of an exemplary insertioninstrument for use in holding, distracting and locking the interspinousspacer assembly shown in FIG. 9;

FIG. 11A illustrates a side perspective view of a sixth preferredembodiment of an interspinous spacer assembly in accordance with thepresent invention;

FIG. 11B illustrates a side perspective view of the interspinous spacerassembly shown in FIG. 11A coupled to adjacent spinous processes;

FIG. 12A illustrates a side perspective view of a seventh preferredembodiment of an interspinous spacer assembly in accordance with thepresent invention;

FIG. 12B illustrates a side elevational view of the interspinous spacerassembly shown in FIG. 12A;

FIG. 13A illustrates a side elevational view of an eighth preferredembodiment of an interspinous spacer assembly according to the presentinvention, the interspinous spacer assembly being in a non-expanded,collapsed configuration;

FIG. 13B illustrates a side elevational view of the interspinous spacerassembly shown in FIG. 13A, the interspinous spacer assembly being in anexpanded, deployed configuration;

FIG. 13C illustrates a side elevational view of the interspinous spacerassembly shown in FIG. 13A, the interspinous spacer assembly being in anincremental configuration between the non-expanded, collapsedconfiguration shown in FIG. 13A and the expanded, deployed configurationshown in FIG. 13B;

FIG. 13D illustrates a side perspective view of the interspinous spacerassembly shown in FIG. 13A coupled to adjacent spinous processes;

FIG. 14A illustrates a side perspective view of a ninth preferredembodiment of an interspinous spacer assembly according to the presentinvention, the interspinous spacer assembly including the interspinousspacer member shown in FIGS. 13A-13D with an adjustable engagementmechanism for adjustably coupling the spacer member to adjacent spinousprocesses;

FIG. 14B illustrates a partial, side perspective view of theinterspinous spacer assembly shown in FIG. 14A;

FIG. 14C illustrates a side perspective view of the interspinous spacerassembly shown in FIG. 14A coupled to adjacent spinous processes;

FIG. 15 illustrates a cross-sectional view of an exemplary linearratchet mechanism for coupling the interspinous spacer assemblies to theadjacent spinous processes;

FIG. 16A illustrates a side perspective view of a tenth preferredembodiment of an interspinous spacer assembly according to the presentinvention, the interspinous spacer assembly including the interspinousspacer member shown in FIGS. 13A-13D with adjustable engagementmechanism for adjustably coupling the spacer member to adjacent spinousprocesses;

FIG. 16B illustrates a partial, side perspective view of theinterspinous spacer assembly shown in FIG. 16A;

FIG. 17 is a cross-sectional view of the interspinous spacer assemblytaken alone line 17-17 from FIG. 16A;

FIG. 18A illustrates a side perspective view of an exemplary spike forcoupling the interspinous spacer assemblies to the adjacent spinousprocesses;

FIG. 18B illustrates an alternate, side perspective view of an exemplaryspike for coupling the interspinous spacer assemblies to the adjacentspinous processes;

FIG. 19 illustrates a side perspective view of an eleventh preferredembodiment of an interspinous spacer assembly according to the presentinvention;

FIG. 19A illustrates a partial, side perspective view of theinterspinous spacer assembly illustrated in FIG. 19 with theinterspinous spacer member having pores;

FIG. 19B illustrates a partial, side perspective view of theinterspinous spacer assembly illustrated in FIG. 19 with theinterspinous spacer member having cavities;

FIG. 20 illustrates a partial, side perspective view of a twelfthpreferred embodiment of an interspinous spacer assembly according to thepresent invention, the interspinous spacer assembly including theinterspinous spacer member shown in FIG. 19 with an adjustableengagement mechanism for adjustably coupling the spacer member toadjacent spinous processes, the adjustable engagement mechanism beingconfigured as a multilevel construct;

FIG. 21 illustrates a partial, side perspective view of a thirteenthpreferred embodiment of an interspinous spacer assembly according to thepresent invention;

FIG. 22 illustrates a side perspective view of the interspinous spacerassembly shown in FIG. 21 coupled to adjacent spinous processes;

FIG. 23A illustrates a side perspective view of a fourteenth preferredembodiment of an interspinous spacer assembly according to the presentinvention;

FIG. 23B illustrates an exploded, side perspective view of theinterspinous spacer assembly shown in FIG. 23A;

FIG. 24A illustrates an anterior perspective view of a fifteenthpreferred embodiment of an interspinous spacer assembly according to thepresent invention;

FIG. 24B illustrates a posterior perspective view of the interspinousspacer assembly shown in FIG. 24A;

FIG. 24C illustrates a posterior perspective view of the interspinousspacer assembly shown in FIG. 24A coupled to adjacent spinous processes;

FIG. 25A illustrates a side perspective view of a sixteenth preferredembodiment of an interspinous spacer assembly according to the presentinvention;

FIG. 25B illustrates an exploded, side perspective view of theinterspinous spacer assembly shown in FIG. 25A;

FIG. 25C illustrates a top elevational view of the interspinous spacerassembly shown in FIG. 25A;

FIG. 25D illustrates a side perspective view of the interspinous spacerassembly of FIG. 25A coupled to adjacent spinous processes;

FIG. 26A illustrates a side perspective view of a seventeenth preferredembodiment of an interspinous spacer assembly according to the presentinvention;

FIG. 26B illustrates an exploded, side perspective view of theinterspinous spacer assembly shown in FIG. 26A; and

FIG. 26C illustrates a side perspective view of the interspinous spacerassembly of FIG. 26A coupled to adjacent spinous processes.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “lower” and “upper”designate directions in the drawings to which reference is made. Thewords “inwardly” and “outwardly” refer to directions toward and awayfrom, respectively, the geometric center of the interspinous spacer anddesignated parts thereof. The words “anterior”, “posterior”, “superior”,“inferior” and related words and/or phrases designate preferredpositions and orientations in the human body to which reference is madeand are not meant to be limiting. The words and phrases “collapse”,“telescopic”, “disposed within”, “slidably disposed within”, “interlock”and related words and/or phrases designate the relationship between twoparts or devices to which reference is made and are not meant tolimiting. The terminology includes the above-listed words, derivativesthereof and words of similar import.

Certain exemplary embodiments of the invention will now be describedwith reference to the drawings. In general, such embodiments relate toan interspinous spacer assembly for implantation and/or affixationbetween spinous processes SP of adjacent vertebrae, including a superiorvertebra Vs and an inferior vertebra Vi to treat spinal stenosis or anycondition wherein spacing between the spinous processes SP of theadjacent vertebrae Vs, Vi is desired.

As will be described in greater detail below, the interspinous spacerassembly preferably includes an interspinous spacer member sized andconfigured for insertion into the space between adjacent spinousprocesses SP and an engagement mechanism for operatively coupling thespacer member to one or more of the adjacent spinous processes SP. Theinterspinous spacer assembly is preferably adjustable so that the usercan configure the interspinous spacer assembly to fit the anatomy of thepatient's spine. The interspinous spacer assembly may be fully orpartially adjustable. For example, the height, width and/or angle of thespacer assembly may be adjustable. Alternatively, only the height, onlythe width or only the angle of the spacer member may be adjustable, orthe spacer member may be non-adjustable. Moreover, the height, widthand/or the angle of the spacer member may be adjustable to only acertain extent or limit. Additionally, the engagement mechanism ispreferably adjustable so that the user can adjust the engagementmechanism such as, for example, the orientation, height, width, etc., asnecessary to engage the patient's spinous processes SP. Alternatively,in some embodiments, the adjustability of the engagement mechanism maybe limited or non-adjustable. Likewise, the method of implanting theinterspinous spacer preferably allows a surgeon to adjust theinterspinous spacer and/or the orientation of the interspinous spacer inthe patient.

The interspinous spacer assembly of the present invention may beimplanted using a number of different approaches. For example, theinterspinous spacer assembly may be inserted laterally into theinterspinous space or it may be implanted via a range of differentposterior approaches, preferably without disruption, damage or removalof the spinal ligaments (e.g. ligaments remain intact), although, theligaments may be disrupted, damaged, cut and/or removed to facilitateimplantation of the interspinous spacer assembly or portions thereof.Although the interspinous spacer assembly of the present inventiongenerally allows for a less invasive implantation procedure, differentembodiments of the present invention may require varying degrees ofinvasiveness during implantation. The lateral approach of implanting theinterspinous spacer assembly may be less invasive than posteriorapproaches. One less invasive implantation procedure, may allow aninterspinous spacer member of the interspinous spacer assembly of thepresent invention to be implanted between adjacent spinous processes SPand be coupled to adjacent spinous processes SP via an engagementmechanism fixed to adjacent spinous processes SP at the interface of thesupra spinous ligament and the spinous processes SP, thus preserving themuscles attached to the spinous processes SP.

The interspinous spacer assembly may be used to treat spinal stenosis incombination with decompression. Alternatively, the interspinous spacerassembly may be used to treat spinal stenosis without any additionaltreatment. Especially in the situation where decompression is used, itis desirable to restore at least part of the stability of the spine withan interspinous spacer assembly.

In use, the interspinous spacer assembly of the present invention, mayallow for application of distractive force as well as a compressiveforce to the same spinal level (e.g. distractive force in case ofextension of the spine and compressive force in case of flexion of thespine).

In certain embodiments of the present invention, the interspinous spacerassembly includes an interspinous spacer member and an engagementmechanism for engaging one or more of the spinous processes SP. Theengagement mechanism may include wings, plates, hooks, etc. that preventmigration of the interspinous spacer assembly. In certain embodimentsthe engagement mechanism may be adjustable in length, bendable,polyaxial with respect to the spacer member, etc. to enable adaptabilityto the individual anatomy of a particular patient's spine and preventmigration of the interspinous spacer assembly once implanted into thepatient. In use, the engagement member may engage the patient's spinousprocesses SP in a variety of different ways including, for example, viaone or more screws, bolts, rivets, spikes, or other protrusions and/orvia compression. The engagement mechanism may be operatively coupled tothe interspinous spacer member or members in a variety of differentways. One having ordinary skill in the art will recognize that thevarious engagement mechanisms described for the preferred embodiments ofthe interspinous spacer assemblies may be adapted and interchangedbetween the interspinous spacer assemblies of preferred embodiments,without significantly impacting the structure and operation of theimplants.

In certain embodiments of the present invention, the interspinous spacermember of the interspinous spacer assembly may be made from severalparts, for example, two interspinous spacer paddles or spacer plates mayfunction as the spacer member, such that each paddle or plate contactsone of the adjacent spinous processes SP. The spacer paddles or platesare preferably adjustable with respect to one another so that the heightof the spacer member can be adjusted or the distance between the paddlescan be modified. Additionally, in other embodiments, the interspinousspacer may be formed by parts that serve multiple functions.

The interspinous spacer assembly and components thereof may be made fromany biocompatible material including but not limited to metals such as,e.g., titanium, titanium alloys, stainless steel, etc., polymers suchas, e.g., PEEK, PCU, etc., and combinations thereof. In the situationwhere the interspinous spacer assembly may be manufactured from PEEK,the combination of an elastic rubber like polymer may be used to allowfor any large deformations and high loads that may be encountered by theinterspinous spacer assembly.

The interspinous spacer assembly may also promote spinal fusion forexample, by constructing the spacer member from a mesh or porous typematerial or structure. Alternatively and/or in addition, perforations orcavities may be formed in the spacer member. The method of implantingthe interspinous spacer assembly may also promote spinal fusion. Forexample, a surgeon implanting the interspinous spacer assembly betweenadjacent spinous processes SP may also implant bone chips or otherbiocompatible implant material that fuses with the adjacent spinalprocesses through cavities or pores formed in the interspinous spacerassembly.

Referring to FIGS. 1-4B, a first preferred embodiment of theinterspinous spacer assembly 100 includes an interspinous spacer member110 sized and configured for insertion into an interspinous spacebetween adjacent spinous processes SP and an engagement mechanism 105for operatively coupling the spacer member 110 to the adjacent spinousprocess SP.

The spacer member 110 may be designed as a non-adjustable, rigid body,although it is envisioned that an adjustable spacer member such as thosedescribed herein with respect to certain of the other preferredembodiments may be used. The spacer member 110 preferably includes acaudal spacer portion 112 for contacting a superior surface of theinferior spinous process SP and a cranial spacer portion 115 forcontacting an inferior surface of the superior spinous process SP. Thebone contacting surfaces of the cranial and caudal spacer portions 115,112 preferably include seats (e.g., concave or U-shaped recesses, SeeFIG. 1) for receiving the adjacent spinous processes SP. In use, thespacer member 110 may be configured such that it is implanted at theposterior ends of the adjacent spinal processes SP or further toward theanterior of the adjacent spinal processes SP.

The spacer member 110 may also include a projection 120 extending fromone or both of the lateral sides thereof for engaging the engagementmechanism 105. In use, the engagement mechanism 105 may be implanted oneither one (unilateral construct) or both sides (bilateral construct) ofthe spacer member 110 and adjacent to the spinous processes SP. Morepreferably, the spacer member 110 includes one or more curvate orspherical projections 120 for engaging a pop-on coupling mechanism 170operatively associated with the engagement mechanism 105, as will bedescribed in greater detail below, so that the engagement mechanism 105may polyaxial rotate with respect to the spacer member 110. Thisconfiguration enables the user to adjust the position of the engagementmechanism 105 with respect to the spacer member 110. It should be notedthat other types of coupling mechanisms may be used, for examples,interconnecting threads, screws, rivets, bolts, etc.

The engagement mechanism 105 may be in the form of one or more plates130, 140 for coupling the spacer member 110 to the adjacent spinousprocesses SP. As shown, the engagement mechanism 105 is preferably inthe form of first and second plate assemblies 130, 140 for coupling thespacer member 110 to the adjacent upper and lower spinous processes SP.

The plate assemblies 130, 140 preferably have adjustable lengths and canbe adjusted to accommodate various fixation angles with respect to thespacer member 110. The adjustability of the lengths of the plates 130,140 is preferably achieved through a telescopic construction of theplates 130, 140. For example, each of the plate assemblies 130, 140 ofthe first preferred embodiment includes a female portion 131, 141 and amale portion 132, 142 whereby the male portion 132, 142 is slidablyreceived within the female portion 131, 141 so that the overall lengthof the assemblies 130, 140 can be adjusted.

The plates assemblies 130, 140 are preferably connected to the adjacentspinous processes SP and/or laminae via one or more bone fixationelements, more preferably bone screws 160. The bone screws 160preferably include an enlarged, curvate or semi-spherical head portion162 and an externally threaded shaft portion 163 for engaging thepatient's spinal processes. The head portion 162 preferably includes amechanism for engaging a screwdriver (not shown). For example, the headportion 162 preferably includes a plurality of recesses for engaging aplurality of projections formed on a tip of a screwdriver, althoughother configurations are envisioned, including but not limited to, aninternal recess, an external hexagon, a star drive pattern, a Phillipshead pattern, a slot for a screw driver, a threading for acorrespondingly threaded post, etc.

The specific features of the shaft 163 including, for example, threadpitch, self drilling configurations, self tapping configurations, shaftdiameter, shaft shape, etc. are interchangeable, and it would beapparent to one having ordinary skill in the art that the bone screws160 are not limited to any particular type of shaft 163 or threadconfiguration. The bone screw 160 may also include a reduced diameterneck portion between the head portion 162 and the shaft portion 163,which accommodates the polyaxial connection of the bone screws 160 tothe plate assemblies 130, 140. The bone screws 160 may further becannulated and fenestrated (not shown) such that openings extendoutwardly from a central hollow channel in a cannulated screw to urgefluid out of the screws 160 during injection or draw fluid into thecentral hollow channel from sides of the screw 160 during extraction ofmaterial adjacent the screws 160.

Referring to FIG. 3A, the screws 160 may include a single head portion162 as is generally known in the art. Alternatively, referring to FIG.3B, the screws 160 may include dual head portions. That is, a secondhead portion 164 may be attached to the threaded shaft portion 163 of afirst bone screw 160 after the first screw 160 has been inserted intoand through the spinous process SP. In this manner, a bilateralconstruct, wherein plates 130, 140 are placed on both lateral sides ofthe spinous processes SP, may be coupled to the same bone screw 160. Itshould be noted, that in bilateral constructs, it is not necessary touse double-headed screws. For example, single head screws may beinserted into the spinous processes SP on both sides of the spinousprocesses SP.

The plate assemblies 130, 140 of the first preferred embodiment can bemounted to the curvate head portion 162 of the bone screws 160 and tothe curvate projection 120 extending from the spacer member 110 by anycoupling means or mechanism now or hereafter known in the art.Preferably, however, the plate assemblies 130, 140 are mounted to thescrews 160 and to the spacer member 110 by a pop-on mechanism 170 sothat the plate assemblies 130, 140 can be coupled to the bone screws 160and the spacer member 110 after the bone screws 160 and the spacermember 110 have been implanted, thus allowing visibility during screwinsertion and simplifying the surgical technique.

Referring to FIG. 4B, the pop-on mechanism 170 of the first preferredembodiment includes a flexible collet 172 having a semi-spherical recess173 for receiving the curvate or semi-spherical head portion 162 of thebone screws 160 and the curvate projection 120 extending from the spacermember 110. The collet 172 includes a threaded second end 174 extendingtherefrom so that the threaded end 174 of the collet 172 may extendthrough a hole or slot formed in the plate assemblies 130, 140 beforeengaging a nut member 176. In use, after the spacer member 110 has beeninserted into the interspinous space, the bone screws 160 have beeninserted into the adjacent spinous processes SP and the plate assemblies130, 140 have been properly orientated and coupled to the bone screws160 and the spacer member 110, the user may rotate the nut member 176,which in turn causes the collet 172 to move with respect to the hole orslot formed in the plate assemblies 130, 140, thereby causing the collet172 to compress against the curvate head portion 162 of the bone screw160 and projection 120 to secure the relative position of the plateassemblies 130, 140 with respect to the spacer member 110 and the bonescrews 160.

In the case of a bilateral construct, the plates 130, 140 are installedon both sides of the interspinous spacer 110 and a second pop-oncoupling mechanism 170 is provided to engage the spherical projection120 extending from the spacer member 110 for coupling the spacer member110 to the additional set of plates 130, 140 as well as coupling theplates 130, 140 to each other.

Alternatively, it is envisioned that one or more spinal rods (not shown)can be used in place of the preferred plates 130, 140. In addition, thebone screws 160 may be secured in the spinous process SP or in thepedicles of the vertebrae Vs, Vi. Alternatively, it is envisioned thatthe system may be used without a spacer member 110 implanted between theadjacent vertebrae Vs, Vi.

Both single and multilevel constructs for implantation of multipleinterspinous spacer assemblies 100 of the first preferred embodiment atmultiple levels are possible and such constructs would be apparent toone having ordinary skill in the art based upon a review of the presentapplication.

Referring to FIGS. 5-6B, a second preferred embodiment of theinterspinous spacer assembly 200 includes an integrated, adjustablespacer member 210 and an engagement mechanism 205 so that theinterspinous spacer assembly 200 can be adapted to various sized spinousprocesses SP and spaces therebetween. The interspinous spacer assembly200 (e.g., spacer member 210 and engagement mechanism 205) is preferablyadjustable in both length and width to conform to the patient's anatomy.The interspinous spacer assembly 200 of the second preferred embodimentincludes four plates portions 230, 235, 240, 245 that form theadjustable spacer member 210 and engagement mechanism 205.

The four plate portions 230, 235, 240, 245 preferably interlock with oneanother to form both the spacer member 210 and lateral plates (i.e.,engagement member 205) used for engaging the spinous processes SP. Forexample, a first plate portion 230 interlocks with a second plateportion 235 to form an inferior portion of the interspinous spacerassembly 200 for contacting the superior portion of the inferior spinousprocess SP while a third plate portion 240 interlocks with a fourthplate portion 245 to form the superior portion of the interspinousspacer assembly 200 for contacting the inferior portion of the superiorspinous process. The first plate portion 230 also interlocks with thethird plate portion 240 to form a first lateral plate for engaging thelateral portions of one side of the adjacent spinous processes SP whilesecond plate portion 235 interlocks with fourth plate portion 245 toform a second lateral plate for engaging the lateral portion of a secondside of the adjacent spinous processes SP.

The plate portions 230, 235, 240, 245 may interlock with one another byany means now or hereafter known for such purpose. The plate portions230, 235, 240, 245 of the second preferred embodiment interlock via aseries of interlocking rails and grooves. For example, as best shown inFIG. 5, the first plate portion 230 includes a plurality of rails 232disposed within and/or between grooves 237 formed in the second plateportion 235 in order to form the inferior portion of the adjustablespacer member 210. In use, the rails 232 are slidably disposable withrespect to the grooves 237 so that the position of the first plateportion 230 may be laterally adjusted with respect to second plateportion 235. Similarly, the first plate portion 230 may include aplurality of rails 234 disposed within and/or between grooves 242 formedin the third plate portion 240 in order to form one of the lateral sideplates. In use, the rails 234 are slidably disposable with respect tothe grooves 242 so that the position of the first plate portion 230 maybe vertically adjusted with respect to the third plate portion 240.Likewise, the fourth plate portion 245 may include a plurality of rails247 disposed within and/or between grooves 244 formed in the third plateportion 240 in order to form the superior portion of the adjustablespacer member 210. In use, the rails 247 are slidably disposable withrespect to the grooves 244 so that the position of the fourth plateportion 245 may be laterally adjusted with respect to the third plateportion 240. Similarly, the fourth plate portion 245 may include aplurality of rails 249 disposed within and/or between grooves 239 formedin the second plate portion 235 in order to form the second lateralplate. In use, the rails 249 are slidably disposable with respect to thegrooves 239 so that the position of the second plate portion 235 may bevertically adjusted with respect to the fourth plate portion 245.

In this manner, the user can fully adjust the height and width of thespacer member 210 of the second preferred embodiment and the height andwidth of the engagement mechanism (i.e., lateral plates 230, 235, 240,245) to conform to the patient's anatomy. The interspinous spacerassembly 200 of the second preferred embodiment is adjustable from afirst, collapsed configuration (as shown in FIG. 6A) so that the heightand width of the spacer member 210 and engagement mechanism (i.e.,lateral plates 230, 235, 240, 245) is minimized to facilitate insertion,to a second, expanded configuration (as shown in FIG. 6B) so that theheight and width of the spacer member 210 and the height and width ofthe engagement mechanism (i.e., lateral plates 230, 235, 240, 245) areincreased. The arrangement of the second preferred embodiment of theinterspinous spacer assembly 200 further enables the user to selectamongst any number of intermediate configurations. Alternatively, in afirst configuration, the interspinous spacer assembly 200 may have aminimized height and a maximized width to facilitate insertion of theinterspinous spacer assembly 200 into the interspinous space, the usermay then distract the interspinous spacer assembly 200 to the desiredheight and then reduce its width so that the assembly holds the spinousprocesses SP between the lateral plates 230, 235, 240, 245.

The second preferred embodiment of the interspinous spacer assembly 200may be manufactured from a polymer such as, for example, PEEK or anyother weldable polymer so that the position of the engagement mechanism(i.e., lateral plates 230, 235, 240, 245) can be secured by, forexample, ultrasonic welding. Alternatively, the interspinous spacerassembly 200 can be manufactured from any other biocompatible materialwherein the position of the engagement mechanism (i.e., lateral plates230, 235, 240, 245) may be secured by any other means including, forexample, mechanical means such as screws, ratchet, etc.

The interspinous spacer assembly 200 of the second preferred embodimentmay be coupled to the spinous processes SP by any means now or hereafterknown in the art. Preferably, the engagement mechanism (i.e., lateralplates 230, 235, 240, 245) is secured to the adjacent spinous processesSP by a bolt mechanism 260. In use, the bolt mechanism 260 is insertedthrough the spinous process SP from one or both sides. For example, asbest shown in FIGS. 6A and 6B, the bolt mechanism 260 may include afemale portion 261 and a male portion 262 extending from the spacerassembly 200 that is laterally insertable into one of the spinousprocesses SP. The preferred male portion 262 is mateable with the femaleportion 261 so that the bolt mechanism 260 adapts to various spinousprocess thicknesses. The bolt mechanism 260 may also include washers265, more preferably spiked washers, for engaging the adjacent spinousprocesses SP. The bolt mechanism 260 may be replaced by any othermechanism for coupling the engagement mechanism 205 to the adjacentspinous processes SP described herein or known for such purposeincluding, for example, threaded bolts and nuts, bone screws, frictionfit, press fit, etc.

Referring to FIG. 7, a third preferred embodiment of the interspinousspacer assembly is similar to the interspinous spacer assembly 200 ofthe second preferred except as noted below. The interspinous spacerassembly 300 of the third preferred embodiment is preferablymanufactured from titanium or similar biocompatible material. In thethird preferred embodiment, an engagement mechanism 305 (i.e., plateportions 330, 335, 340, 345) preferably includes single interlockingmale and female portions (as opposed to a plurality of interlocking railand grooves as described above in connection with interspinous spacerassembly 200). For example, a second plate portion 335 include a singlefemale portion or recess 337 for engaging a single male portion 347extending from a fourth plate portion 345 so that the fourth plateportion 345 is telescopingly received within the second plate portion335. Similarly, a third plate portion 340 includes a single femaleportion or recess 342 for engaging a single male portion 332 extendingfrom a first plate portion 330 so that the first plate portion 330 istelescopingly received within the third plate portion 340. Likewise, thesecond plate portion 335 includes a single female portion or recess 339for engaging a single male portion 334 extending from the first plateportion 330 so that the first plate portion 330 is telescopinglyreceived within the second plate portion 335 and the third plate portion340 includes a single female portion or recess 344 for engaging a singlemale portion (not shown) extending from the fourth plate portion 345 sothat the fourth plate portion 345 is telescopingly received within thethird plate portion 340. Although it is envisioned that each plateportion 330, 335, 340, 345 may include more than one interlocking maleand female portion.

In the construction of the third preferred embodiment of theinterspinous process spacer assembly 300, the user can fully adjust theheight and width of the spacer member 305 and the height and width ofthe engagement mechanism (i.e., lateral plates 330, 335, 340, 345) toconform to the patient's anatomy. The interspinous spacer assembly 300of the third preferred embodiment is adjustable from a first, collapsedconfiguration so that the height and width of the spacer member 310 andengagement mechanism (i.e., lateral plates 330, 335, 340, 345) isminimized, to a second, expanded configuration so that the height andwidth of the spacer member 310 and the height and width of theengagement mechanism (i.e., lateral plates 330, 335, 340, 345) ismaximized. The arrangement of the third preferred embodiment of thespinous spacer assembly 300 further enables the user to select amongstany number of intermediate configurations between the expanded andcollapsed configurations. Alternatively, in a first configuration, theinterspinous spacer assembly 300 of the third preferred embodiment mayhave a minimized height and a maximized width to facilitate insertion ofthe interspinous spacer assembly 300 into the interspinous space, theuser may then distract the interspinous spacer assembly 300 to thedesired height and reduce its width so that the assembly holds thespinous processes SP between the lateral plates 330, 335, 340, 345.

After the interspinous spacer assembly 300 of the third preferredembodiment is adjusted to adapt to the patient's anatomy, the positionof the engagement mechanism (i.e., lateral plates 330, 335, 340, 345)may be secured to one another by any mechanism known in the artincluding, but not limited to, friction fit, press-fit, a boltmechanism, a ratchet mechanism, etc. Preferably, the position of theengagement mechanism (i.e., lateral plates 330, 335, 340, 345) issecured by set screws 380.

In addition, the interspinous spacer assembly 300 of the third preferredembodiment may be coupled to the adjacent spinous processes SP by anymeans now or hereafter known in the art. For example, as shown, thespacer assembly 300 may be secured to the adjacent spinous processes SPwith rotatable spikes 361, which, in use, may be engaged via a tool androtated to engage and/or pierce the spinous processes SP. The rotatablespike 361 may include a series of smaller spikes for engaging thespinous process SP surrounded by a larger central spike for piercing thespinous process SP. Alternatively, the spikes 361 may be ratchetablycoupled to the engagement mechanism (i.e., lateral plates 330, 335, 340,345) so that the spikes 361 can be linearly (i.e., non-rotatably) movedinto engagement with the adjacent spinous processes SP. In anotherarrangement, the rotatable spikes 361 for fixing the engagementmechanism (i.e., lateral plates 330, 335, 340, 345) to the spinousprocesses SP may be replaced with a linear ratchet mechanism, shown inFIG. 15 and described below. In other arrangements, the rotatable spikes361 for fixing the engagement mechanism (i.e., lateral plates 330, 335,340, 345) to the spinous processes SP may be replaced by any othermechanism described herein or known for such purpose including, forexample, a bolt mechanism, rivets, threaded bolts and nuts, bone screws,etc.

Referring to FIG. 8, a fourth preferred embodiment of the interspinousspacer assembly 400 is similar to the interspinous spacer assembly 300of the third preferred embodiment except as noted below. In the fourthpreferred embodiment, the position of the engagement mechanism (i.e.,lateral plates 430 (not shown), 435, 440 (not shown), 445) may besecured by a ratchet-mechanism 450 that is integrally formed with theengagement mechanism 405.

More specifically, second and fourth plate portions 435, 445 preferablyinclude a single interlocking male and female portion. For example, thesecond plate portion 435 includes a single female portion or recess 437for engaging a single male portion 447 extending from the fourth plateportion 445 so that the fourth plate portion 445 may be telescopinglyreceived within the second plate portion 435. However, it is envisionedthat the second and fourth plate portions 435, 445 of the fourthpreferred embodiment may include more than one interlocking male andfemale portion.

In use, the user can fully adjust the height and width of the spacermember 410 and the height and width of the engagement mechanism (i.e.,lateral plates 435, 445) to conform to the patient's anatomy. Theposition of the lateral plates 435, 445 are preferably fixed withrespect to one another via a ratchet mechanism 450. As shown in FIG. 8,for example, the fourth plate portion 445 may include a projection 448extending from the male portion 447, the projection 448 having aplurality of teeth for engaging a recess 451 formed in the femaleportion 437 of the second plate portion 435, the recess 451 having aplurality of grooves for interlocking with the plurality of teeth formedon the projection 448.

Referring to FIG. 9, a fifth preferred embodiment of an interspinousspacer assembly 500 includes an interspinous spacer member 510 having acranial spacer paddle 512 for contacting an inferior surface of thesuperior spinous process SP and a caudal spacer paddle 515 forcontacting a superior surface of the inferior spinous process SP. Thecranial spacer paddle 512 is preferably movable with respect to thecaudal spacer paddle 515 so that the height of the spacer member 510 canbe adjusted to fit a patient's anatomy.

The cranial spacer paddle 512 is preferably integrally formed with theengagement mechanism 505, which is in the form of cranial wings 540, 545for coupling the cranial spacer paddle 512 to the superior adjacentspinous process SP. Likewise, the caudal spacer paddle 515 is preferablyintegrally formed with caudal wings 530 for coupling the caudal spacerpaddle 515 to the inferior adjacent spinous process SP. However, as willbe readily appreciated by one of ordinary skill in the art, the cranialand caudal spacer paddles 512, 515 may be separately formed andoperatively coupled to the cranial and caudal wings 540, 545, 530, 535by any means now or hereafter known for such purpose.

The caudal spacer paddle 515 and the caudal wings 530 preferably includean integrated rack assembly 531, which is telescopingly received in arecess 541 formed in the cranial spacer paddle 512 and the cranial wings540, 545 thereby adjustably couple the cranial spacer paddle 512 to thecaudal spacer paddle 515 so that the height of the interspinous spacerassembly 500 of the fifth preferred embodiment can be adjusted. Onceproperly positioned, a set screw (not shown) disposed in a screw recess581 may be used to secure the position of the interspinous spacerassembly 500.

The caudal spacer paddle 515 and the caudal wings 530 and the cranialspacer paddle 512 and the cranial wings 540, 545 preferably includerecesses 585, 586, respectively, for reasons that will be describedbelow.

In use, the cranial and caudal wings 530, 540, 545 may be coupled to theadjacent spinous processes SP by a bolt mechanism 560, as previouslydescribed. Alternatively, the cranial and caudal wings 530, 540, 545 maybe coupled to the adjacent spinous processes SP by any other mechanismdescribed herein or known for such purposes.

Referring to FIG. 10, an exemplary insertion instrument 590 isillustrated for inserting the interspinous spacer assembly 500 of thefifth preferred embodiment. The insertion instrument 590 preferablyincludes a handle 591, a multilayer screw shaft 592 having a tool tip593, a holding knob 594, a distracting knob 595 and a locking knob 596.The tool tip 593 of the multilayer screw shaft 592 preferably includes aset screw engaging device for engaging the set screw disposed in screwrecess 581 for securing the cranial and caudal paddles 512, 515.

In use, the tool tip 593 preferably includes a plurality of hooks 593 afor engaging the recesses 585, 586 formed in the interspinous spacerassembly 500 of the fifth preferred embodiment. The tool tip 593 isoperatively associated with the holding knob 594 so that rotation of theholding knob 594 firmly couples the interspinous spacer assembly 500 tothe insertion tool 590. The assembly distracting device of themultilayer screw shaft 592 operatively engages the rack assembly 531 andthe set screw engaging device operatively engages the set screw disposedin the screw recess 581 so that rotation of the assembly distractingknob 595 distracts or moves the cranial spacer paddle 512 with respectto the caudal spacer paddle 515 thereby adjusting the height of theinterspinous spacer assembly 500. Once the interspinous spacer assembly500 has been properly positioned, the assembly locking knob 596 isrotated, which in turn, rotates the set screw engaging device and hencethe set screw disposed in the screw recess 581 to secure the position ofthe cranial spacer paddle 512 with respect to the caudal spacer paddle515. Reverse rotation of the assembly holding knob 594 releases the tool590 from the interspinous spacer assembly 500.

As illustrated and described in connection with FIG. 9, the width of theinterspinous spacer assembly 500 is preferably nonadjustable. However,as will be appreciated by one of ordinary skill in the art, the width ofthe interspinous spacer assembly 500 of the fifth preferred embodimentmay be adjustable by any means disclosed herein or known. In addition,the angulation of the cranial and caudal wings 530, 540, 545 may beadjusted by varying the location that wings 530, 540, 545 are fixed tothe spinous processes SP. Alternatively, the cranial and caudal wings530, 540, 545 may be separately and adjustably coupled to the cranialand caudal paddles 512, 515.

Referring to FIGS. 11A and 11B, a sixth preferred embodiment of aninterspinous spacer assembly 600 includes an interspinous spacer member610 and an engagement mechanism 605. In the sixth preferred embodiment,the engagement mechanism 605 includes lateral plates 630, 640. Thelateral plates 630, 640 are preferably constructed such that the heightof the interspinous spacer assembly 600 is non-adjustable. Theinterspinous spacer member 610 operates as a tension band betweenadjacent spinous processes SP by being fixed at the interface of thesupra spinous ligament and the spinous processes SP, as shown in FIG.11B, thus preserving the muscles attached to the spinous processes SPand enabling a relatively less invasive implantation procedure.Alternatively, as will be readily appreciated by one of ordinary skillin the art, the lateral plates 630, 640 may be replaced by adjustableheight plates as described herein or known for such purposes.

The lateral plates 630, 640 are preferably coupled to one another by anymeans herein described or known for such purpose. In addition, thelateral plates 630, 640 may be coupled to the adjacent spinous processesSP by any means herein described or known for such purpose. For example,the lateral plates 630, 640 of the sixth preferred embodiment arecoupled to one another by one or more threaded bolt and nut assemblies670 and include a plurality of spikes 660 extending from an innersurface thereof so that, in use, rotation of the bolt and nut assemblies670 compresses the lateral plates 630, 640 together and presses thespikes 660 into the spinous processes SP for securing the position ofthe interspinous spacer assembly 600.

The interspinous spacer member 610 of the sixth preferred embodimentincludes a cranial paddle 612 for contacting an inferior surface of thesuperior spinous process SP, a caudal paddle 615 for contacting asuperior surface of the inferior spinous process SP and a spreadingelement 620 for adjusting the height of the spacer member 610. Thecranial and caudal paddles 612, 615 may be integrally formed with oneanother or they may be separately formed and operatively associated withone another. The cranial and caudal paddles 612, 615 may be operativelycoupled to the plate portions 630, 640 by any means now or hereafterknown. The spreading element 620 preferably includes a threaded shaft625 and an enlarged head portion 626. In use, rotation of the threadedshaft 625 causes the enlarged end portion 626 to move towards thelateral plates 630, 640, thereby spreading the cranial and caudalpaddles 612, 615 and adjusting the height and, preferably, the angle ofthe interspinous spacer member 610 of the sixth preferred embodiment.The interspinous spacer member 610 may be inserted through the supraspinous ligament or laterally into the interspinous space.

Referring to FIGS. 12A and 12B, a seventh preferred embodiment of theinterspinous spacer assembly 700 includes a cranial spacer paddle 712for contacting an inferior surface of the superior spinous process SPand a caudal spacer paddle 715 for contacting a superior surface of theinferior spinous process, the cranial spacer paddle 712 being moveablewith respect to the caudal spacer paddle 715 so that the overall heightof interspinous spacer member 710 can be adjusted. The bone contactingsurfaces of the cranial and caudal paddles 712, 715 may include aplurality of ridges 725 for contacting the adjacent spinous processesSP. The ridges 725 may also be in the form of spikes or teeth. Inaddition, the bone contacting surface of the cranial paddle 712 may becurved while the bone contacting surface of the caudal paddle 715 may beflat or generally planar for optimally conforming to the naturalcurvature of the spinous processes SP.

The position of the cranial and caudal paddles 712, 715, and hence theheight of the interspinous spacer member 710, may be adjusted by anymechanism herein described or known for such purpose. Preferably, thecranial paddle 712 is integrally formed with or coupled to wings 740,745 and the caudal paddle 715 is integrally formed with or coupled towings 730, 735, wherein the wings 740, 745, 730, 735 are telescopicallyassociated with one another. As a result, because the cranial and caudalpaddles 712, 715 of the interspinous spacer member 710 are integratedwith the wings 730, 735, 740, 745, adjustment of the height of theinterspinous spacer member 710 also adjusts the overall height of theinterspinous spacer assembly 700.

In use, the wings 730, 735, 740, 745 are preferably configured as plateportions, more preferably bendable plate portions so that the wings 730,735, 740, 745 can be adjusted to engage spinous processes SP of variousthicknesses. The wings 730, 735, 740, 745 may be fixed to the spinousprocesses SP by any mechanism herein described or known for suchpurposes including screws, rivets, etc.

The cranial and caudal spacer paddles 712, 715 may be configured so thatthey interconnect when the height of the interspinous spacer member 710is minimized. This may be achieved by including a recess 713 formed inthe cranial paddle 712 for receiving a raised portion 716 formed on thecaudal paddle 715.

Referring to FIGS. 13A-D, an eighth preferred embodiment of theinterspinous spacer assembly 800 includes only an interspinous spacermember 810. The interspinous spacer member 810 preferably includes acranial spacer portion 812 for contacting an inferior surface of thesuperior spinous process SP, a caudal spacer portion 815 for contactinga superior surface of the inferior spinous process SP, wherein thecranial spacer portion 812 is moveable with respect to the caudal spacerportion 815 so that the overall height of interspinous spacer member 810can be adjusted. The bone contacting surfaces of the cranial and caudalportions 812, 815 may include a plurality of ridges 825 for contactingthe adjacent spinous processes SP. The ridges 825 may also be in theform of spikes or teeth. In addition, the bone contacting surface of thecranial portion 812 may be curved while the bone contacting surface ofthe caudal portion 815 may be flat to adapt to the natural curvature ofthe spinous processes SP.

The interspinous spacer member 810 of the eighth preferred embodiment isadjustable from a non-expanded, collapsed configuration (as shown inFIG. 13A) to an expanded, deployed configuration (as shown in FIG. 13B).In addition, the interspinous spacer member 810 is preferably configuredto be incrementally adjustable as well (as exemplary illustrated in FIG.13C). The cranial spacer portion 812 and the caudal spacer portion 815may be interconnected by any means described herein, or any means nowknown or later discovered for such purpose. Preferably, the cranialspacer portion 812 and the caudal spacer portion 815 are interconnectedby a ratchet-type mechanism 830 on the anterior and posterior ends ofthe spacer member 810. For example, the caudal spacer portion 815 mayinclude a plurality of teeth 816 for engaging one or more correspondingteeth 813 formed on the cranial spacer portion 812.

In use, the interspinous spacer member 810 may be adapted by the user tothe patient's anatomy during implantation by adjusting the height of thespacer member 810. Moreover, as will be appreciated by one or ordinaryskill in the art, the angulation of the spacer member 810 may beadjusted by independently adjusting the anterior and posterior ends ofthe spacer member 810.

Referring to FIGS. 14A-C, a ninth preferred embodiment of theinterspinous spacer assembly 900 is similar to the interspinous spacermember 810 of the eight preferred embodiment as described above inconnection with FIGS. 13A-D. Thus, additional discussion of theinterspinous spacer member 910 of the ninth preferred embodiment isomitted herein for the sake of brevity. In this ninth preferredembodiment, the interspinous spacer assembly 900 includes an engagementmechanism 905 for coupling the interspinous spacer member 910 to theadjacent spinous processes SP.

The engagement mechanism 905 preferably is in the form of telescopicplate portions 930, 935, 940, 945. That is, similar to previousembodiments discussed above, the engagement mechanism 905 may includefirst, second, third and fourth plate portions 930, 935, 940, 945wherein the fourth plate portion 945 includes a male portion 946slidably disposed within a female portion or recess 936 formed in thesecond plate portion 935 so that the fourth plate portion 945 istelescopingly received within the second plate portion 935 to form afirst lateral plate. Similarly, the third plate portion 940 may includea male portion (not shown) slidably disposed within a female portion orrecess (not shown) formed in the first plate portion 930 so that thirdplate portion 940 is telescopingly received within the first plateportion 930 to form a second lateral plate. However, it is envisionedthat each plate portion 930, 935, 940, 945 may include more than oneinterlocking male and female portion. The position of the first andsecond lateral plates may be fixed by one or more set screws 980. Asshown, the first and second plate portions 930, 935 may be curved toassist with securement to the adjacent spinous processes SP.

One or more of the plate portions 930, 935, 940, 945 of the ninthpreferred embodiment includes a motion limiting element 950. As shown,the motion limiting element 950 may be in the form of a pin extendingfrom an inner surface of one or more of the plate portions 930, 935,940, 945. In use, the motion limiting element 950 passes through aninterior space of the interspinous spacer member 910. The pin 950 limitsthe amount that the interspinous spacer member 910 can move posteriorlyor anteriorly, but allows the interspinous spacer member 910 tootherwise float freely to enable better adaptation to the individualpatient's anatomy. The interspinous spacer member 910 is preferablyfixed laterally by the plate portions 930, 935, 940, 945.

The engagement mechanism 905 (e.g., plate portions 930, 935, 940, 945)may be coupled to the adjacent spinous processes SP by any meansdescribed herein, or any means now known or later discovered for suchpurpose. Preferably, the engagement mechanism 905 (e.g., plate portions930, 935, 940, 945) is coupled to the adjacent spinous processes SP byan interlocking linear ratchet mechanism 960, a cross-sectional view ofwhich is shown in FIG. 15. Each interlocking linear ratchet mechanism960 includes an externally toothed male portion 961 for ratchetablyengaging an internally toothed female portion 962. Each of the toothedmale and female portions 961, 962 preferably include a sharp, leadingedge for cutting into the spinous processes SP during insertion. In use,the male portion 961 and the female portion 962 are inserted into theadjacent spinous processes SP from opposite lateral sides until thetoothed portions of the male and female portions 961, 962 interlock withone another. Thereafter, the male and female portions 961, 962 may becompressed in a ratcheting manner to compress the engagement mechanism905 (e.g., plate portions 930, 935, 940, 945) against the adjacentspinous processes SP. The male and female portions 961, 962 may becompressed by any mechanism now or hereafter known for such purpose. Forexample, a compression tool such as compression forceps, can be used toengage the interlocked male and female portions 961, 962. Actuation ofthe compression tool compresses the male and female portions 961, 962and hence compresses the engagement mechanism 905 (e.g., plate portions930, 935, 940, 945) against the adjacent spinous processes SP.Alternatively, the male and female portions 961, 962 may includecorresponding threads so that the male and female portions 961, 962 maybe threadably coupled to one another. Alternatively, the teeth formed onthe male and female portions 961, 962 may be sized and configured to beeither threadably coupled to one another or linearly actuated.

Referring to FIGS. 16A-18B, a tenth preferred embodiment of theinterspinous spacer assembly 1000 includes an interspinous spacer member1010 that is substantially the same as the interspinous spacer members810, 910 of the eight and ninth preferred embodiments. Thus, additionaldiscussion of the interspinous spacer member 1010 of the tenth preferredembodiments is omitted herein for the sake of brevity. In this tenthpreferred embodiment, a motion limiting mechanism 1050 is in the form ofa stabilization rod engaged to, for example, a caudal spacer portion1015 for attaching the caudal spacer portion 1015 to an engagementmechanism 1005 while still allowing a cranial spacer portion 1012 toremain adjustable.

Similar to previous embodiments discussed above, the engagementmechanism 1005 preferably includes first, second, third and fourthtelescopic members or plates 1030, 1035, 1040, 1045 including adjustablemale and female portions so that the length of the engagement mechanism1005 can be adjusted. The position and/or length of the engagementmechanism 1005 (i.e., telescopic members or plates 1030, 1035, 1040,1045) may be secured via a compressive force via rotation of a set screw1080. For example, referring to FIG. 17, the second telescopic member orplate 1035 may include a bore 1036 housing a compression nut 1037 foraccepting one side of the stabilization rod 1050. Depending on thetightness of the set screw 1080, the compression nut 1037 will remainloose allowing the interspinous spacer member 1010 to rotate about anaxis of the stabilization rod 1050 or the compression nut 1037 willbecome tightened to fix the position of the spacer member 1010.

The engagement mechanism 1005 (i.e., telescopic members or plates 1030,1035, 1040, 1045) may be coupled to the adjacent spinous processes SP byany means described herein, or any means now known or later discoveredfor such purpose. Preferably, as shown in FIGS. 18A and 18B, theengagement mechanism 1005 (i.e., telescopic members or plates 1030,1035, 1040, 1045) may be attached to the spinous processes SP by one ormore spikes 1060. The spikes 1060 may be of various shapes known in theart, but the spikes 1060 preferably include a semicircular shape (asshown in FIG. 18A) or a pyramid shape (as shown in FIG. 18B).

Referring to FIG. 19, an eleventh preferred embodiment of theinterspinous spacer assembly 1100 includes an interspinous spacer member1110 having a cranial spacer paddle 1112 for contacting an inferiorsurface of the superior spinous process SP and a caudal spacer paddle1115 for contacting a superior surface of the inferior spinous process.The cranial spacer paddle 1112 is preferably moveable with respect tothe caudal spacer paddle 1115 so that the overall height of interspinousspacer member 1110 can be adjusted. The engagement mechanism 1105preferably includes first, second, third and fourth telescopic membersor plates 1130, 1135, 1140, 1145, similar to previous embodimentsdescribed above.

The interspinous spacer assembly 1100 of the eleventh preferredembodiment is depicted with its ventral (or anterior) side up toillustrate that the width of the cranial spacer paddle 1112 and thecaudal spacer paddle 1115 tapered toward the ventral edge of the paddles1112, 1115, wherein such tapered configuration aids implantation and maybe used in any embodiment described herein. The bone contacting surfaceof the cranial spacer paddle 1112 may be curved for engaging theinferior surface of the superior spinous process SP while the bonecontacting surface of the caudal paddle 1115 may be flat for adapting tothe natural curvature of the spinal processes SP. Referring to FIG. 19A,the cranial spacer paddle 1112 and/or the caudal spacer paddle 1115 mayinclude pores or perforations 1113. The pores or perforations 1113 maypermit bone growth into the spacer paddles 1112, 1115. Referring to FIG.19B, the cranial spacer paddle 1112 and/or the caudal spacer paddle 1115may alternatively include cavities 1114. The cavities 1114 may permitbone growth and fusion through the spacer paddles 1112, 1115. Theconfigurations of interspinous spacer member 1110 of the eleventhpreferred embodiment with pores or perforations 1113 or with cavities1114 may be applied to all the embodiments of the present invention,although it is not shown in the illustrative figures for otherembodiments.

The cranial and caudal spacer paddles 1112, 1115 preferably includeprojections 1120, more preferably cylindrical projections, extendingtherefrom for engaging the engagement mechanism 1105 so that theorientation (e.g., angle) of the cranial and caudal spacer paddles 1112,1115 can be adjusted. That is, by coupling the cranial and caudal spacerpaddles 1112, 1115 to the engagement mechanism 1105 via cylindricalprojections 1120, the cranial and caudal spacer paddles 1112, 1115 areallowed to rotate about their axes to thereby allow better adaptation ofthe interspinous spacer member 1110 within the interspinous space.

The cylindrical projections 1120 formed on the cranial and caudal spacerpaddles 1112, 1115 are preferably received in bores 1125, preferablycylindrical bores, formed in the engagement mechanism 1105 (i.e.,telescopic members or plates 1130, 1135, 1140, 1145).

Furthermore, by coupling the cranial and caudal spacer paddles 1112,1115 to the engagement mechanism 1105, the height of the interspinousspacer member 1110 is adjusted via adjustment of the engagementmechanism 1105 (i.e., telescopic members or plates 1130, 1135, 1140,1145). That is, similar to previous embodiments discussed above, bytelescopically adjusting the length of the engagement mechanism 1105(i.e., telescopic members or plates 1130, 1135, 1140, 1145), the user isable to simultaneously adjust the height of the spacer member 1110,which is coupled thereto.

The engagement mechanism 1105 (i.e., telescopic members or plates 1130,1135, 1140, 1145) is preferably outfitted with a stopper to limit themaximum extension of the engagement mechanism 1105 (i.e., telescopicmembers or plates 1130, 1135, 1140, 1145) and to prevent disassembly ofthe interspinous spacer assembly 1100. The stopper may be achieved inany number of ways known to those in the art. For example, one or moreof the members or plates may include a radiussed flange 1136.

The position of the first, second, third and fourth telescopic membersor plates 1130, 1135, 1140, 1145 may be fixed by any mechanism known inthe art including, for example, via a set screw. Preferably, theposition of the first, second, third and fourth telescopic members orplates 1130, 1135, 1140, 1145 is fixed via a bolt assembly, including abolt 1170, a nut 1171 and an optional spacer 1172. Tightening of thebolt assembly preferably fixes the position of the first, second, thirdand fourth telescopic members or plates 1130, 1135, 1140, 1145 and fixesthe angle of the cranial and caudal paddles 1112, 1115.

The engagement mechanism 1105 (i.e., telescopic members or plates 1130,1135, 1140, 1145) is preferably bendable so that it may be adapted tovarious spinous process thicknesses. One way of making the engagementmechanism 1105 (i.e., telescopic members or plates 1130, 1135, 1140,1145) bendable is to taper or form a groove therein so that thetelescopic members or plates 1130, 1135, 1140, 1145 bend at apre-defined location.

The engagement mechanism 1105 (i.e., telescopic members or plates 1130,1135, 1140, 1145) may be coupled to the adjacent spinous processes SP byany means described herein, or any means now known or later discoveredfor such purpose, including, for example, via rivets, screws or otherfixation techniques. Preferably, the engagement mechanism 1105 (i.e.,telescopic members or plates 1130, 1135, 1140, 1145) is fixed to theadjacent interspinous processes SP by of a bolt mechanism 1160, aspreviously described and illustrated in FIG. 15.

Referring to FIG. 20, one lateral side of a twelfth preferred embodimentof an interspinous spacer assembly 1200 includes a spacer member 1210and an engagement mechanism 1205 that are similar to the spacer member1110 and the engagement mechanism 1105 of the interspinous spacerassembly 1100 of the eleventh preferred embodiment. Thus, additionaldiscussion of the interspinous spacer member 1210 and engagementmechanism 1205 of the twelfth preferred embodiment is omitted herein forthe sake of brevity. In this twelfth preferred embodiment, theinterspinous spacer assembly 1200 is constructed as a multilevelconstruct having a plurality of bores 1225 for receiving two or moreinterspinous spacer members 1210, each including cranial and caudalspacer paddles 1212, 1215, as described above. In addition, theengagement mechanism 1205 (i.e., telescopic members or plates 1230,1235, 1240, 1245) is interconnected via one or more additional membersso that the engagement mechanism 1205 (i.e., telescopic members orplates 1230, 1235, 1240, 1245) can span multiple levels and engagemultiple interspinous spacer members 1210. As shown, telescopic membersor plates 1230, 1245 are interconnected by first and second telescopicextension members 1280, 1290 forming a series of plate portions tocreate one lateral plate that is adjustable in length and capable ofspanning multiple levels.

In use, the first telescopic extension member 1280 is telescopicallycoupled to the fourth plate 1245. Likewise the second telescopicextension member 1290 is telescopically coupled to the first plate 1230.Finally, the second telescopic extension member 1290 is telescopicallyreceived in the first extension member 1280. As will be readilyappreciated by one of ordinary skill in the art, the interspinous spacerassembly 1200 of the twelfth preferred embodiment can include any numberof extension members including, but not limited to, one, three, four ormore. The interspinous spacer assembly 1200 may or may not be coupled toone or more intermediate spinous processes SP and the coupling may beaccomplished by any means described herein, or any means now known orlater discovered for such purpose.

Referring to FIGS. 21 and 22, a thirteenth preferred embodiment of theinterspinous spacer assembly 1300 is constructed as a multi-levelconstruct so that the interspinous spacer assembly 1300 can engagemultiple levels, although a single level construct of the interspinousspacer assembly 1300 is also envisioned. The interspinous spacerassembly 1300 includes two interspinous spacer members 1310, eachincluding a cranial spacer paddle 1312 for contacting an inferiorsurface of the superior spinous process SP and a caudal spacer paddle1315 for contacting a superior surface of the inferior spinous processSP, wherein the cranial spacer paddle 1312 is moveable with respect tothe caudal spacer paddle 1315 so that the overall height of interspinousspacer member 1310 can be adjusted. The bone contacting surfaces of thepaddles 1312, 1315 may include a plurality of ridges 1325 for contactingthe adjacent spinous processes SP. The ridges 1325 may also be spikes orteeth. In addition, the bone contacting surface of the cranial paddle1312 may be curved while the bone contacting surface of the caudalpaddle 1315 may be flat for conforming to the natural curvature of thespinous processes SP. It should be noted that the interspinous spacerassembly 1300 may include any number of interspinous spacer members 1310including one, three, four or more.

The interspinous spacer assembly 1300 is shown with its ventral oranterior side up to illustrate that the width of the cranial and caudalspacer paddles 1312, 1315 may be tapered toward the ventral or anterioredge of the paddles 1312, 1315. This tapered configuration may beapplied to all the embodiments of the present invention, although it isnot shown in the illustrative figures for certain other embodiments.

The cranial and caudal paddles 1312, 1315 may be operatively coupled tothe engagement mechanism 1305 by any means described herein, or known inthe art for such purpose. Preferably the cranial and caudal paddles1312, 1315 include cylindrical projections 1320 extending therefrom forbeing received within cylindrical bores or slots 1325 formed in theengagement mechanism 1305 so that the cranial and caudal paddles 1312,1315 can rotate with respect to the engagement mechanism 1305 to betterconform with the adjacent spinous processes SP.

In this thirteenth preferred embodiment, the engagement mechanism 1305is preferably in the form of a plate assembly 1330 including integratedsliding plate assemblies 1350. That is, the engagement mechanism 1305preferably includes first and second lateral plates 1330, 1340, whereineach lateral plate 1330, 1340 includes a recess formed therein forslidably receiving sliding plate assemblies 1350. The sliding plateassemblies 1350 are operatively coupled to at least one of the cranialand caudal spacer paddles 1312, 1315 so that movement of the slidingplate assemblies 1350 with respect to the lateral plates 1330, 1340moves the cranial and/or caudal spacer members 1312, 1315 and henceadjusts the overall height of the interspinous spacer member 1310.

The sliding plate assemblies 1350 are preferably coupled to the lateralplate 1330, 1340 via a ratchet-type mechanism so that the position ofthe sliding plate assemblies 1350, and hence the position of the cranialand caudal spacer members 1312, 1315 can be incrementally adjusted,although it is envisioned that other coupling mechanism may be usedincluding, for example, a tongue and groove type system. The slidingplate assemblies 1350 preferably include the bores and/or slots 1325 foraccommodating the protrusions 1320 extending from the cranial and caudalspacer member 1312, 1315.

In use, the sliding plate assemblies 1350 are adjustable with respect tothe lateral plate 1330, 1340 so that the position of the cranial spacerpaddle 1312 and caudal spacer paddle 1315 can be adjusted relative toone another to thereby adjust the longitudinal location of theinterspinous spacer member 1310 as well as the height of theinterspinous spacer member 1310.

The engagement mechanism 1305 of the thirteenth preferred embodiment maybe coupled to the adjacent spinous processes SP by any means describedherein, or any means now known or later discovered for such purpose.Preferably, as shown, the engagement mechanism 1305 is coupled to theadjacent spinous processes SP via a bolting mechanism 1360 as previousdescribed. The interspinous spacer assembly 1300 may or may not becoupled to one or more intermediate spinous processes SP and thecoupling may be accomplished by any means described herein, or any meansnow known or later discovered for such purpose.

Referring to FIGS. 23A and 23B, a fourteenth preferred embodiment of theinterspinous spacer assembly 1400 includes an interspinous spacer member1410 having a cranial spacer part 1412 for contacting an inferiorsurface of a superior spinous process SP, a caudal spacer part 1415 forcontacting a superior surface of an inferior spinous process SP, and anintermediate spacer part 1420 that is slidably disposed between thecranial spacer part 1412 and the caudal spacer part 1415. In use,multiple intermediate spacer parts 1420 of various heights may beprovided to enable the user to select the appropriate size so that theoverall height of the interspinous spacer member 1410 can be adjusted tosuit the user's particular needs and the patient's specific anatomy.

The bone contacting surfaces of the cranial and caudal spacer parts1412, 1415 may include a plurality of ridges 1425 for contacting theadjacent spinous processes SP. The ridges 1425 may also be spikes orteeth. In addition, the bone contacting surface of the cranial spacerpart 1412 may be curved while the bone contacting surface of the caudalspacer part 1415 may be flat for conforming to the natural curvature ofthe spinal processes SP.

The cranial spacer part 1412, the caudal spacer part 1415 and theintermediate spacer part 1420 may be coupled together by any mechanismknown in the art including, for example, bonding, welding, screw, rivet,thread, etc. Preferably, the cranial spacer part 1412 includes a recess(not shown) formed on an inner surface thereof for engaging a projection1422 extending from an upper surface of the intermediate spacer part1420, or vice versa. Similarly, the intermediate spacer part 1420includes a recess 1424 formed on an inner surface thereof for engaging aprojection 1417 extending from an upper surface of the caudal spacerpart 1415, or vice versa.

The engagement mechanism 1405 of the interspinous spacer assembly 1400of the fourteenth preferred embodiment is in the form of integral wings1430, 1435, 1440, 1445 with one wing (shown as 1440) integrally formedwith the cranial spacer part 1412, one wing (shown as wing 1430)integrally formed with the caudal spacer part 1415 and two wings (shownas 1435 and 1445) integrally formed with the intermediate spacer part1420. However, as readily appreciated by one of ordinary skill in theart, the wings 1430, 1435, 1440, 1445 may be separated from andoperatively coupled to the cranial spacer part 1412, caudal spacer part1415 and intermediate spacer part 1420 by any mechanism described hereinor known in the art for such purpose. Each of the wings 1430, 1435,1440, 1445 may include a pad 1447 for contacting the spinous processesSP. The wings 1430, 1435, 1440, 1445 and/or pads 1447 can be fixed tothe spinous processes SP by any mechanism described herein or known inthe art for such purpose including but not limited to spikes, screws,rivets, bolts, etc.

In use, the interspinous spacer assembly 1400 is implanted by firstimplanting the cranial spacer part 1412 and the caudal spacer part 1415in a collapsed configuration into the interspinous space from a firstlateral side of the adjacent spinous processes SP and then distracted tothe desired height. Once the desired distraction is achieved, thecorresponding intermediate spacer part 1420 of a compatible height isinserted into the interspinous space and between the cranial spacer part1412 and the caudal spacer part 1415 from a second lateral side of theadjacent spinous processes SP.

Referring to FIGS. 24A-C, a fifteenth preferred embodiment of theinterspinous spacer assembly 1500 includes an interspinous spacer member1510 and an engagement mechanism 1505 in the form of first and secondlateral plates 1530, 1540. The interspinous spacer member 1510 ispreferably in the form of a rigid, non-adjustable spacer member (i.e.,fixed width and height spacer member), although other configurationsincluding adjustable height spacer members as described herein areenvisioned. The spacer member 1510 includes a cranial surface 1512 forcontacting an inferior surface of the superior spinous process SP, acaudal surface 1515 for contacting a superior surface of the inferiorspinous process SP, a ventral or anterior end 1517 and a dorsal orposterior end 1518. The ventral or anterior end 1517 preferablyprotrudes anteriorly beyond anterior edges of the lateral plates 1530,1540 while the posterior or dorsal end 1518 preferably is flush with theposterior edges of the lateral plates 1530, 1540. The ventral oranterior end 1517 may also include a tapered width for facilitatinginsertion of the spacer member 1510 into the interspinous space. Theposterior or dorsal end 1518 preferably includes a threaded borehole1519 for threadably engaging a distal end of an insertion tool (notshown).

The interspinous spacer member 1510 may be coupled to the lateral plates1530, 1540 by any mechanism described herein or known in the art forsuch purpose. Preferably, the interspinous spacer member 1510 includes abore for receiving clips 1520 projecting from holes 1532 formed in thelateral plates 1530, 1540. Incorporation of the clips 1520 and holes1532 preferably enables the interspinous spacer member 1510 to rotateand shift in any direction with respect to the lateral plates 1530, 1540so that, in use, the interspinous spacer member 1510 can be rotated andshifted to adjust its angulation and position.

Once the interspinous spacer assembly 1500 has been properly positioned,the position of the spacer member 1510 can be fixed with respect to thelateral plates 1530, 1540 by, for example, inserting and rotating a toolin threaded borehole 1519 or rotating a set screw or other mechanisminto engagement with the clips 1520. Alternatively, the spacer member1510 may be left to rotate freely with respect to the lateral plates1530, 1540.

The engagement mechanism 1505 (e.g., lateral plates 1530, 1540) may becoupled to the adjacent spinous processes SP by any mechanism describedherein or known in the art for such purpose. Preferably, the engagementmechanism 1505 (e.g., lateral plates 1530, 1540) is coupled to theadjacent spinous processes SP by spikes 1560 extending from an innersurface thereof. More preferably, the spikes 1560 of the first lateralplate 1530 extend into and through the spinous processes SP so that theypierce the opposite lateral side of the spinous processes SP and thespikes 1560 are received within a corresponding hole 1561 formed in thesecond lateral plate 1540.

Referring to FIGS. 25A-D, a sixteenth preferred embodiment of theinterspinous spacer assembly 1600 includes an interspinous spacer member1610 having a non-adjustable, rigid spacer body, although otherconfigurations are envisioned including adjustable height spacer membersas described herein. The interspinous spacer member 1610 preferablyincludes a bore 1611 extending therethrough.

The engagement mechanism 1605 preferably is in the form of rotatablefirst, second, third and fourth wings 1630, 1635, 1640, 1645 extendingfrom the spacer member 1610 for laterally engaging the spinous processesSP on both lateral sides of the spinous processes SP, preferably at thebase of the spinous process SP (i.e., junction to lamina where bone isstrongest). The first wing 1630 preferably includes a shaft 1670, morepreferably a threaded shaft, extending perpendicularly therefrom, theshaft 1670 being sized and configured to pass through a bore 1611 formedin the interspinous spacer member 1610. The second, third and fourthwings 1635, 1640, 1645 preferably each include a bore 1636, 1641, 1646,respectively, for receiving the shaft 1670 so that the shaft 1670extends through the bores 1636, 1641, 1646 formed in the second, thirdand fourth wings 1635, 1640, 1645 and the bore 1611 formed in the spacermember 1610.

More specifically, the interspinous spacer shaft 1670 is preferablyintegrated with the rotatable first wing 1630. The rotatable fourth wing1645 preferably includes a cylindrically arranged vessel 1647 configuredto slide over the interspinous spacer shaft 1670 and mate with acorresponding cylindrical vessel 1642 formed on the third rotatable wing1640 to form a cylinder around the interspinous spacer shaft 1670. Thecylinder formed by the vessels 1642, 1647 of the third and fourthrotatable wings 1640, 1645 are sized and configured to be slidablydisposed within the bore 1611 formed in the spacer member 1610. Thethird rotatable wing 1635 is also placed on the interspinous spacershaft 1670, which has threads to accommodate a fastening nut 1675, whichpreferably has grooves for accepting a tool to tighten the fastening nut1675. In use, with the fastening nut 1675 in a loosened state, thefirst, second, third and fourth rotatable wings 1630, 1635, 1640, 1645are fully rotatable so that they may be are properly positioned by theuser on either side of the adjacent spinous processes SP. Once properlypositioned, rotation of the fastening nut 1675 tightens the rotatablewings 1630, 1635, 1640, 1645 relative to one another.

The rotatable wings 1630, 1635, 1640, 1645 allow the interspinous spacerassembly 1600 to be introduced in a minimal invasive approach in afolded configuration as best shown in FIG. 25C. Thereafter, the user candeploy the wings 1630, 1635, 1640, 1645 by rotating them into properposition, after the interspinous spacer assembly 1600 has beenpositioned within the interspinous space between adjacent spinousprocesses SP.

Referring to FIGS. 26A-C, a seventeenth preferred embodiment of theinterspinous spacer assembly 1700 includes an interspinous spacer member1710 and an engagement mechanism 1705. The interspinous spacer member1710 is preferably constructed as a non-adjustable, rigid spacer memberwhile the engagement mechanism 1705 is preferably in the form of aplurality of hooks 1730, 1735, 1740, 1745 connected to the interspinousspacer member 1710. Preferably, the hooks 1730, 1735, 1740, 1745 areconnected to the spacer member 1710 via a cable 1750 so that theposition of the hooks 1730, 1735, 1740, 1745 can be adjusted withrespect to the spacer member 1710.

The interspinous spacer member 1710 preferably includes a hole 1711extending therethrough for receiving a bolt 1770. The ends of the cables1750 are spirally wound so that the ends of the cables 1750 can bereceived by, and preferably wrapped around reels 1771 that areoperatively associated with bolt 1770. The interspinous spacer member1710 may also include deploying holes 1722 for enabling the cables 1750to pass therethrough. In use, rotation of the bolt 1770 in a firstdirection deploys the cables 1750 and the hooks 1730, 1735, 1740, 1745with respect to the spacer member 1710 while rotation of the bolt 1770in a second direction retracts the cables 1750, and the hooks 1730,1735, 1740, 1745, with respect to the spacer member 1710.

In use, the cranial hooks 1730, 1735 are preferably attached to thecranial edge of the lamina of the cranial vertebra while the caudalhooks 1740, 1745 are preferably attached to the caudal edge of thelamina of the caudal vertebra, on either lateral side of the spinousprocesses SP, as best shown in FIG. 26C. After attachment of the laminahooks 1730, 1735, 1740, 1745, rotation of the bolt 1770 retracts anyslack in the cables 1750 thus tightening the cables 1750, fixing theposition of the interspinous spacer member 1710, and applyingcompression to the spinal segments.

While the foregoing description and drawings represent preferredembodiments of the present invention, it will be understood that variousadditions, modifications and substitutions may be made therein withoutdeparting from the spirit and scope of the present invention as definedin the accompanying claims. In particular, it will be clear to thoseskilled in the art that the present invention may be embodied in otherspecific forms, structures, arrangements, proportions, and with otherelements, materials, and components, without departing from the spiritor essential characteristics thereof. One skilled in the art willappreciate that the invention may be used with many modifications ofstructure, arrangement, proportions, materials, and components andotherwise, used in the practice of the invention, which are particularlyadapted to specific environments and operative requirements withoutdeparting from the principles of the present invention. In addition,features described herein may be used singularly or in combination withother features. That is, features from one embodiment may be used incombination with or in place of features from another embodiment. Thepresently disclosed embodiments are therefore to be considered in allrespects as illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims, and not limited to the foregoingdescription.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as described in the appended claims.

We claim:
 1. An interspinous spacer assembly for insertion into aninterspinous space between a spinous process of a superior vertebralbody and a spinous process of an inferior vertebral body, the assemblycomprising: an interspinous spacer member sized and configured forinsertion into the interspinous space, the spacer member including acranial surface for contacting an inferior surface of the spinousprocess of the superior vertebral body, a caudal surface for contactinga superior surface of the spinous process of the inferior vertebralbody, a ventral end and a dorsal end that defines an threaded borehole,a set screw received within the threaded borehole, and a spacer boreextending through the interspinous spacer member; and an engagementmechanism that includes a first lateral plate and a second lateral platefor operatively coupling the spacer member to the spinous processes ofthe superior and inferior vertebral bodies, the first and second lateralplates each defining an interior surface that extends inward toward theinterior surface of the opposing lateral plate, the engagement mechanismincluding a collapsible rod having a proximal end and a distal end eachreceived within a plate bore provided in each of the first and secondlateral plates, respectively, the proximal end connected to a firstportion of the collapsible rod and the distal end connected to a secondportion of the collapsible rod, the first portion and the second portionof the collapsible rod extending from the plate bore into the spacerbore, the proximal and distal ends of the collapsible rod not extendingbeyond an outside surface of the corresponding first and second lateralplates, wherein the first portion and the second portion of thecollapsible rod are moveable relative to each other to narrow a distancebetween the first lateral plate and the second lateral plate to causethe first lateral plate and the second lateral plate to fix theengagement mechanism to the spinous processes, wherein the set screwfixes the position of the first portion and second portion of thecollapsible rod, thereby fixing the position of the first lateral plateand the second lateral plate with respect to the interspinous spacermember; wherein the ventral end has a tapered width for facilitatinginsertion of the interspinous spacer member into the interspinous space,the tapered width defined by a left surface and opposing right surfaceeach extending between the cranial and caudal surfaces.
 2. Theinterspinous spacer assembly of claim 1, wherein the first portion andthe second portion of the collapsible rod each include a frictionalengagement portion to engage the first portion with the second portion.3. The interspinous spacer assembly of claim 2, wherein a compressiontool engages the first portion and the second portion to apply asubstantially equal but opposite force on the first portion and thesecond portion, respectively, such that the first portion and the secondare compressed together.
 4. The interspinous spacer assembly of claim 2,wherein the frictional engagement portion is a toothed portion.
 5. Theinterspinous spacer assembly of claim 1, wherein the engagementmechanism comprises spikes that extend from an inner surface of each ofthe first lateral plate or the second lateral plate, and wherein thespikes are adapted to extend into and through the spinous processes. 6.The interspinous spacer assembly of claim 5, wherein the spikes have asemicircular shape.
 7. The interspinous spacer assembly of claim 5,wherein the spikes have a pyramid shape.
 8. The interspinous spacerassembly of claim 5, wherein the spikes that extend from the innersurface of the first lateral plate engage a corresponding receiving holein the second lateral plate, and wherein the spikes that extend from thesecond lateral plate engage a corresponding receiving hole in the firstlateral plate.
 9. The interspinous spacer assembly of claim 1, whereinthe collapsible rod extends through the interspinous spacer member. 10.An interspinous spacer assembly for insertion into an interspinous spacebetween a spinous process of a superior vertebral body and a spinousprocess of an inferior vertebral body, the assembly comprising: aninterspinous spacer member sized and configured for insertion into theinterspinous space, the spacer member including a cranial surface forcontacting an inferior surface of the spinous process of the superiorvertebral body, a caudal surface for contacting a superior surface ofthe spinous process of the inferior vertebral body, a ventral end and adorsal end, the dorsal end including a threaded borehole, a set screwreceived within the threaded borehole, and a spacer bore extendingthrough the interspinous spacer member; and an engagement mechanism thatincludes a first lateral plate and a second lateral plate foroperatively coupling the spacer member to the spinous processes of thesuperior and inferior vertebral bodies, the first and second lateralplates each defining an interior surface that extends inward toward theinterior surface of the opposing lateral plate, and a first clip and asecond clip for operatively coupling the spacer member with the firstand second lateral plates, the first clip and the second clip receivedwithin a plate bore extending through each of the first and secondlateral plates, respectively, and into the spacer bore, the first clipand the second clip not extending beyond an outside surface of thecorresponding first and second lateral plates, the engagement mechanismcomprising spikes that extend from an inner surface of each of the firstlateral plate or the second lateral plate, the spikes adapted to extendinto and through the spinous processes to fix the engagement mechanismto the spinous processes, wherein the set screw fixes the position ofthe first clip and the second clip, thereby fixing the position of thefirst lateral plate and the second lateral plate with respect to theinterspinous spacer member; wherein the ventral end has a tapered widthfor facilitating insertion of the interspinous spacer member into theinterspinous space, the tapered width defined by a left surface and anopposing right surface each extending between the cranial and caudalsurfaces.
 11. The interspinous spacer assembly of claim 10, whereininterspinous spacer member is a rigid, non-adjustable spacer memberhaving a fixed width and a fixed height.
 12. The interspinous spacerassembly of claim 10, wherein the interspinous spacer member isrotatable about the first and second clip with respect to the engagementmechanism.
 13. The interspinous spacer assembly of claim 12, wherein theinterspinous spacer member is fixed with respect to the first lateralplate and the second lateral plate by the set screw inserted into thethreaded borehole engaging the first and second clips.
 14. Theinterspinous spacer assembly of claim 10, wherein the spikes have asemicircular shape.
 15. The interspinous spacer assembly of claim 10,wherein the spikes have a pyramid shape.
 16. The interspinous spacerassembly of claim 10, wherein the ventral end extends anteriorly beyondan anterior edge of the engagement mechanism and the dorsal end issubstantially flushed with a posterior edge of the engagement mechanism.17. The interspinous spacer assembly of claim 10, wherein the spikesthat extend from the inner surface of the first lateral plate engage acorresponding receiving hole in the second lateral plate, and whereinthe spikes that extend from the second lateral plate engage acorresponding receiving hole in the first lateral plate.
 18. Theinterspinous spacer assembly of claim 10, wherein the spikes comprise alinear ratchet mechanism having a first toothed portion provided on thefirst lateral plate and a second toothed portion provided on the secondlateral plate, and wherein the first toothed portion engages within thesecond toothed portion to fix the engagement mechanism to the spinousprocesses.
 19. The interspinous spacer assembly of claim 18, wherein thelinear ratchet mechanism comprises one of a bolt mechanism, rivets,threaded bolts and nuts and bone screws.